Does screen writer count? My favorite story author is Joe Straczinsky (Babylon 5).
Also would like to see Vernor Vinge +/- Orson Scott Card. As well as Neal Stephenson, William Gibson, David Brin, Timothy Zahn, or James Hogan. Also Harry Turtledove whose famous for alternate histories.

I find it sad that a list of most popular Sci-Fi writers does not include someone from India. My favorite writer is "Desi Babu" from India, who has written some amazing Sci-Fi stories. Check out this one, called "The Useless Dust" to read an
India flavored Sci Fi story:
http://peanutexpress.blogspot.in/2012/01/useless-dust-part-i.html

My current favorite hard sci-fi author is Dan Simmons. His Hyperion and Endymion novels are fantastic, best I have ever read. He also wrote a "horror" book, "Children of the Night", which adds a modern spin on the Vlad the Impaler/vampire legend.